Lung Volume and Breathing Quiz

Lung Volume

• Lung volume, or lung capacity, is the maximum volume of air that can be held in the lungs.
• The average male adult lung volume is 6 liters, while the average female's is 5.2-4 liters (10-12% smaller).
• Lung volume is influenced by height and gender, affecting the size of the thoracic cavity and lungs.
• During quiet breathing, only about 0.5 liters of air are inhaled and exhaled.

Spirometer

• A spirometer measures lung capacity.
• Different types exist, including wet spirometers, which use a tube connected to an inverted container floating on water. The expelled air displaces water.

Spirograph

• A spirograph represents the amount of air moving in and out of the lungs with each breath.
• The graph shows the volume of air in the lungs over time.

Lung Volume and Breathing

• Tidal volume is the volume of air breathed in and out in one normal breath. Typically around 0.50 L.
• Only about 0.35 L of air reaches the alveoli; the rest fills the trachea, bronchi, and bronchioles.
• With an average respiratory rate of 12-20 breaths per minute, 4.2-7 L of air is exchanged per minute.
• Inspiratory reserve volume is the additional volume of air that can be inhaled beyond a normal breath. It involves expanding the lungs, using neck and abdominal muscles along with the diaphragm and intercostal muscles.
• Expiratory reserve volume is the additional volume of air that can be exhaled beyond a normal breath.

Capacity Definitions

• Inspiratory capacity is the total amount of air that can be inhaled. This is the sum of tidal volume and inspiratory reserve volume.
• Vital capacity is the total volume of gas that can be moved in and out of the lungs. This is the sum of inspiratory capacity + expiratory reserve volume.
• Total lung volume is the total amount of gas that can be held in the lungs and is equal to the sum of vital capacity and residual volume.
• Residual volume is the amount of gas remaining in the lungs and airways after a forced exhalation. This prevents lung collapse (~1L).

Factors Affecting Lung Volume

• Exercise: Extended exercise increases lung capacity and tidal volume.
• Illness: Illness can decrease vital capacity and tidal volume by affecting the number of alveoli or weakening the breathing muscles. Tidal volume and vital capacity are reduced.

Patient Data Analysis

• A table of patient data, showing tidal volume, vital capacity, and respiratory rates, is included and used to answer questions related to a long-distance runner or someone with a respiratory disorder.
• Key differences between tidal volume and vital capacity include that tidal volume describes regular breathing; vital capacity shows maximum air intake/exhale.
• Based on the data, patient #5 is likely a long-distance runner, having the largest vital capacity and a lower respiratory rate.
• Patient #3 is potentially suffering from a respiratory disorder – they show a lower than average tidal volume with a higher than average respiratory rate.